implement optimizations

src/commonMain/kotlin/com/infendro/bytes/ByteOrder.kt

@@ -0,0 +1,5 @@
+package com.infendro.bytes
+
+enum class ByteOrder {
+    BIG_ENDIAN, LITTLE_ENDIAN;
+}

src/commonMain/kotlin/com/infendro/bytes/bytearray/Conversion.kt

@@ -0,0 +1,32 @@
+package com.infendro.bytes.bytearray
+
+import com.infendro.bytes.ByteOrder
+import com.infendro.bytes.ByteOrder.BIG_ENDIAN
+import com.infendro.bytes.ubytearray.toInt
+import com.infendro.bytes.ubytearray.toLong
+import com.infendro.bytes.ubytearray.toUInt
+import com.infendro.bytes.ubytearray.toULong
+
+fun ByteArray.toUInt(startIndex: Int = 0, order: ByteOrder = BIG_ENDIAN) =
+    asUByteArray().toUInt(startIndex, order)
+
+fun ByteArray.toInt(startIndex: Int = 0, order: ByteOrder = BIG_ENDIAN) =
+    asUByteArray().toInt(startIndex, order)
+
+fun ByteArray.toUIntArray(order: ByteOrder = BIG_ENDIAN) =
+    UIntArray(size / 4).also { copyInto(it, order = order) }
+
+fun ByteArray.toIntArray(order: ByteOrder = BIG_ENDIAN) =
+    IntArray(size / 4).also { copyInto(it, order = order) }
+
+fun ByteArray.toULong(startIndex: Int = 0, order: ByteOrder = BIG_ENDIAN) =
+    asUByteArray().toULong(startIndex, order)
+
+fun ByteArray.toLong(startIndex: Int = 0, order: ByteOrder = BIG_ENDIAN) =
+    asUByteArray().toLong(startIndex, order)
+
+fun ByteArray.toULongArray(order: ByteOrder = BIG_ENDIAN) =
+    ULongArray(size / 8).also { copyInto(it, order = order) }
+
+fun ByteArray.toLongArray(order: ByteOrder = BIG_ENDIAN) =
+    LongArray(size / 8).also { copyInto(it, order = order) }

src/commonMain/kotlin/com/infendro/bytes/bytearray/Copy.kt

@@ -0,0 +1,37 @@
+package com.infendro.bytes.bytearray
+
+import com.infendro.bytes.ByteOrder
+import com.infendro.bytes.ByteOrder.BIG_ENDIAN
+import com.infendro.bytes.ubytearray.copyInto
+
+fun ByteArray.copyInto(
+    destination: UIntArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) = asUByteArray().copyInto(destination, destinationOffset, startIndex, endIndex, order)
+
+fun ByteArray.copyInto(
+    destination: IntArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) = asUByteArray().copyInto(destination, destinationOffset, startIndex, endIndex, order)
+
+fun ByteArray.copyInto(
+    destination: ULongArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) = asUByteArray().copyInto(destination, destinationOffset, startIndex, endIndex, order)
+
+fun ByteArray.copyInto(
+    destination: LongArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) = asUByteArray().copyInto(destination, destinationOffset, startIndex, endIndex, order)

src/commonMain/kotlin/com/infendro/bytes/bytearray/Operators.kt

@@ -0,0 +1,70 @@
+package com.infendro.bytes.bytearray
+
+import com.infendro.bytes.ubytearray.*
+
+fun ByteArray.invInto(
+    destination: ByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+) = asUByteArray().invInto(destination.asUByteArray(), destinationOffset, startIndex, endIndex)
+
+fun ByteArray.inv() =
+    (asUByteArray().inv()).asByteArray()
+
+fun ByteArray.andInto(
+    that: ByteArray,
+    destination: ByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    thatStartIndex: Int = 0,
+) = asUByteArray().andInto(
+    that.asUByteArray(),
+    destination.asUByteArray(),
+    destinationOffset,
+    startIndex,
+    endIndex,
+    thatStartIndex,
+)
+
+infix fun ByteArray.and(that: ByteArray) =
+    (this.asUByteArray() and that.asUByteArray()).asByteArray()
+
+fun ByteArray.orInto(
+    that: ByteArray,
+    destination: ByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    thatStartIndex: Int = 0,
+) = asUByteArray().orInto(
+    that.asUByteArray(),
+    destination.asUByteArray(),
+    destinationOffset,
+    startIndex,
+    endIndex,
+    thatStartIndex,
+)
+
+infix fun ByteArray.or(that: ByteArray) =
+    (this.asUByteArray() or that.asUByteArray()).asByteArray()
+
+fun ByteArray.xorInto(
+    that: ByteArray,
+    destination: ByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    thatStartIndex: Int = 0,
+) = asUByteArray().xorInto(
+    that.asUByteArray(),
+    destination.asUByteArray(),
+    destinationOffset,
+    startIndex,
+    endIndex,
+    thatStartIndex,
+)
+
+infix fun ByteArray.xor(that: ByteArray) =
+    (this.asUByteArray() xor that.asUByteArray()).asByteArray()

src/commonMain/kotlin/com/infendro/bytes/int/Conversion.kt

@@ -0,0 +1,16 @@
+package com.infendro.bytes.int
+
+import com.infendro.bytes.ByteOrder
+import com.infendro.bytes.ByteOrder.BIG_ENDIAN
+
+fun Int.toUByteArray(order: ByteOrder = BIG_ENDIAN) =
+    UByteArray(4).also { copyInto(it, order = order) }
+
+fun Int.toByteArray(order: ByteOrder = BIG_ENDIAN) =
+    ByteArray(4).also { copyInto(it, order = order) }
+
+fun IntArray.toUByteArray(order: ByteOrder = BIG_ENDIAN) =
+    UByteArray(size * 4).also { copyInto(it, order = order) }
+
+fun IntArray.toByteArray(order: ByteOrder = BIG_ENDIAN) =
+    ByteArray(size * 4).also { copyInto(it, order = order) }

src/commonMain/kotlin/com/infendro/bytes/int/Copy.kt

@@ -0,0 +1,33 @@
+package com.infendro.bytes.int
+
+import com.infendro.bytes.ByteOrder
+import com.infendro.bytes.ByteOrder.BIG_ENDIAN
+import com.infendro.bytes.uint.copyInto
+
+fun Int.copyInto(
+    destination: UByteArray,
+    destinationOffset: Int = 0,
+    order: ByteOrder = BIG_ENDIAN,
+) = toUInt().copyInto(destination, destinationOffset, order)
+
+fun Int.copyInto(
+    destination: ByteArray,
+    destinationOffset: Int = 0,
+    order: ByteOrder = BIG_ENDIAN,
+) = toUInt().copyInto(destination, destinationOffset, order)
+
+fun IntArray.copyInto(
+    destination: UByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) = asUIntArray().copyInto(destination, destinationOffset, startIndex, endIndex, order)
+
+fun IntArray.copyInto(
+    destination: ByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) = asUIntArray().copyInto(destination, destinationOffset, startIndex, endIndex, order)

src/commonMain/kotlin/com/infendro/bytes/long/Conversion.kt

@@ -0,0 +1,16 @@
+package com.infendro.bytes.long
+
+import com.infendro.bytes.ByteOrder
+import com.infendro.bytes.ByteOrder.BIG_ENDIAN
+
+fun Long.toUByteArray(order: ByteOrder = BIG_ENDIAN) =
+    UByteArray(8).also { copyInto(it, order = order) }
+
+fun Long.toByteArray(order: ByteOrder = BIG_ENDIAN) =
+    ByteArray(8).also { copyInto(it, order = order) }
+
+fun LongArray.toUByteArray(order: ByteOrder = BIG_ENDIAN) =
+    UByteArray(size * 8).also { copyInto(it, order = order) }
+
+fun LongArray.toByteArray(order: ByteOrder = BIG_ENDIAN) =
+    ByteArray(size * 8).also { copyInto(it, order = order) }

src/commonMain/kotlin/com/infendro/bytes/long/Copy.kt

@@ -0,0 +1,33 @@
+package com.infendro.bytes.long
+
+import com.infendro.bytes.ByteOrder
+import com.infendro.bytes.ByteOrder.BIG_ENDIAN
+import com.infendro.bytes.ulong.copyInto
+
+fun Long.copyInto(
+    destination: UByteArray,
+    destinationOffset: Int = 0,
+    order: ByteOrder = BIG_ENDIAN,
+) = toULong().copyInto(destination, destinationOffset, order)
+
+fun Long.copyInto(
+    destination: ByteArray,
+    destinationOffset: Int = 0,
+    order: ByteOrder = BIG_ENDIAN,
+) = toULong().copyInto(destination, destinationOffset, order)
+
+fun LongArray.copyInto(
+    destination: UByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) = asULongArray().copyInto(destination, destinationOffset, startIndex, endIndex, order)
+
+fun LongArray.copyInto(
+    destination: ByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) = asULongArray().copyInto(destination, destinationOffset, startIndex, endIndex, order)

src/commonMain/kotlin/com/infendro/bytes/ubytearray/Conversion.kt

@@ -0,0 +1,57 @@
+package com.infendro.bytes.ubytearray
+
+import com.infendro.bytes.ByteOrder
+import com.infendro.bytes.ByteOrder.BIG_ENDIAN
+import com.infendro.bytes.ByteOrder.LITTLE_ENDIAN
+
+fun UByteArray.toUInt(startIndex: Int = 0, order: ByteOrder = BIG_ENDIAN): UInt {
+    require(startIndex in 0..(size - 4))
+
+    return when (order) {
+        BIG_ENDIAN -> {
+            (this[startIndex].toUInt() shl 24) or (this[startIndex + 1].toUInt() shl 16) or
+                    (this[startIndex + 2].toUInt() shl 8) or this[startIndex + 3].toUInt()
+        }
+        LITTLE_ENDIAN -> {
+            this[startIndex].toUInt() or (this[startIndex + 1].toUInt() shl 8) or
+                    (this[startIndex + 2].toUInt() shl 16) or (this[startIndex + 3].toUInt() shl 24)
+        }
+    }
+}
+
+fun UByteArray.toInt(startIndex: Int = 0, order: ByteOrder = BIG_ENDIAN) =
+    toUInt(startIndex, order).toInt()
+
+fun UByteArray.toUIntArray(order: ByteOrder = BIG_ENDIAN) =
+    UIntArray(size / 4).also { copyInto(it, order = order) }
+
+fun UByteArray.toIntArray(order: ByteOrder = BIG_ENDIAN) =
+    IntArray(size / 4).also { copyInto(it, order = order) }
+
+fun UByteArray.toULong(startIndex: Int = 0, order: ByteOrder = BIG_ENDIAN): ULong {
+    require(startIndex in 0..(size - 8))
+
+    return when (order) {
+        BIG_ENDIAN -> {
+            (this[startIndex].toULong() shl 56) or (this[startIndex + 1].toULong() shl 48) or
+                    (this[startIndex + 2].toULong() shl 40) or (this[startIndex + 3].toULong() shl 32) or
+                    (this[startIndex + 4].toULong() shl 24) or (this[startIndex + 5].toULong() shl 16) or
+                    (this[startIndex + 6].toULong() shl 8) or this[startIndex + 7].toULong()
+        }
+        LITTLE_ENDIAN -> {
+            this[startIndex].toULong() or (this[startIndex + 1].toULong() shl 8) or
+                    (this[startIndex + 2].toULong() shl 16) or (this[startIndex + 3].toULong() shl 24) or
+                    (this[startIndex + 4].toULong() shl 32) or (this[startIndex + 5].toULong() shl 40) or
+                    (this[startIndex + 6].toULong() shl 48) or (this[startIndex + 7].toULong() shl 56)
+        }
+    }
+}
+
+fun UByteArray.toLong(startIndex: Int = 0, order: ByteOrder = BIG_ENDIAN) =
+    toULong(startIndex, order).toLong()
+
+fun UByteArray.toULongArray(order: ByteOrder = BIG_ENDIAN) =
+    ULongArray(size / 8).also { copyInto(it, order = order) }
+
+fun UByteArray.toLongArray(order: ByteOrder = BIG_ENDIAN) =
+    LongArray(size / 8).also { copyInto(it, order = order) }

src/commonMain/kotlin/com/infendro/bytes/ubytearray/Copy.kt

@@ -0,0 +1,85 @@
+package com.infendro.bytes.ubytearray
+
+import com.infendro.bytes.ByteOrder
+import com.infendro.bytes.ByteOrder.BIG_ENDIAN
+import com.infendro.bytes.ByteOrder.LITTLE_ENDIAN
+
+fun UByteArray.copyInto(
+    destination: UIntArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) {
+    val length = endIndex - startIndex
+    require(length >= 0 && length % 4 == 0)
+    require(startIndex in 0..(size - length))
+    require(destinationOffset in 0..(destination.size - (length / 4)))
+
+    when (order) {
+        BIG_ENDIAN -> {
+            repeat(length / 4) { i ->
+                destination[destinationOffset + i] =
+                    (this[startIndex].toUInt() shl 24) or (this[startIndex + 1].toUInt() shl 16) or
+                            (this[startIndex + 2].toUInt() shl 8) or this[startIndex + 3].toUInt()
+            }
+        }
+        LITTLE_ENDIAN -> {
+            repeat(length / 4) { i ->
+                destination[destinationOffset + i] =
+                    this[startIndex].toUInt() or (this[startIndex + 1].toUInt() shl 8) or
+                            (this[startIndex + 2].toUInt() shl 16) or (this[startIndex + 3].toUInt() shl 24)
+            }
+        }
+    }
+}
+
+fun UByteArray.copyInto(
+    destination: IntArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) = copyInto(destination.asUIntArray(), destinationOffset, startIndex, endIndex, order)
+
+fun UByteArray.copyInto(
+    destination: ULongArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) {
+    val length = endIndex - startIndex
+    require(length >= 0 && length % 8 == 0)
+    require(startIndex in 0..(size - length))
+    require(destinationOffset in 0..(destination.size - (length / 8)))
+
+    when (order) {
+        BIG_ENDIAN -> {
+            repeat(length / 4) { i ->
+                destination[destinationOffset + i] =
+                    (this[startIndex].toULong() shl 56) or (this[startIndex + 1].toULong() shl 48) or
+                            (this[startIndex + 2].toULong() shl 40) or (this[startIndex + 3].toULong() shl 32) or
+                            (this[startIndex + 4].toULong() shl 24) or (this[startIndex + 5].toULong() shl 16) or
+                            (this[startIndex + 6].toULong() shl 8) or this[startIndex + 7].toULong()
+            }
+        }
+        LITTLE_ENDIAN -> {
+            repeat(length / 4) { i ->
+                destination[destinationOffset + i] =
+                    this[startIndex].toULong() or (this[startIndex + 1].toULong() shl 8) or
+                            (this[startIndex + 2].toULong() shl 16) or (this[startIndex + 3].toULong() shl 24) or
+                            (this[startIndex + 4].toULong() shl 32) or (this[startIndex + 5].toULong() shl 40) or
+                            (this[startIndex + 6].toULong() shl 48) or (this[startIndex + 7].toULong() shl 56)
+            }
+        }
+    }
+}
+
+fun UByteArray.copyInto(
+    destination: LongArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) = copyInto(destination.asULongArray(), destinationOffset, startIndex, endIndex, order)

src/commonMain/kotlin/com/infendro/bytes/ubytearray/Operators.kt

@@ -0,0 +1,105 @@
+package com.infendro.bytes.ubytearray
+
+fun UByteArray.invInto(
+    destination: UByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+) {
+    val length = endIndex - startIndex
+    require(length >= 0)
+    require(startIndex in 0..(size - length))
+    require(destinationOffset in 0..(destination.size - length))
+
+    repeat(length) { i ->
+        destination[destinationOffset + i] = this[startIndex + i].inv()
+    }
+}
+
+fun UByteArray.inv() = UByteArray(size).also { invInto(it) }
+
+private inline fun UByteArray.combineInto(
+    that: UByteArray,
+    destination: UByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    thatStartIndex: Int = 0,
+    combine: (UByte, UByte) -> UByte,
+) {
+    val length = endIndex - startIndex
+    require(length >= 0)
+    require(startIndex in 0..(size - length))
+    require(thatStartIndex in 0..(that.size - length))
+    require(destinationOffset in 0..(destination.size - length))
+
+    repeat(length) { i ->
+        destination[destinationOffset + i] = combine(this[startIndex + i], that[thatStartIndex + i])
+    }
+}
+
+private inline fun UByteArray.combine(
+    that: UByteArray,
+    combine: (UByte, UByte) -> UByte,
+): UByteArray {
+    require(this.size == that.size)
+
+    return UByteArray(size).also { combineInto(that, it, combine = combine) }
+}
+
+fun UByteArray.andInto(
+    that: UByteArray,
+    destination: UByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    thatStartIndex: Int = 0,
+) = combineInto(
+    that,
+    destination,
+    destinationOffset,
+    startIndex,
+    endIndex,
+    thatStartIndex,
+) { a, b -> a and b }
+
+infix fun UByteArray.and(that: UByteArray) =
+    combine(that) { a, b -> a and b }
+
+fun UByteArray.orInto(
+    that: UByteArray,
+    destination: UByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    thatStartIndex: Int = 0,
+) = combineInto(
+    that,
+    destination,
+    destinationOffset,
+    startIndex,
+    endIndex,
+    thatStartIndex,
+) { a, b -> a or b }
+
+infix fun UByteArray.or(that: UByteArray) =
+    combine(that) { a, b -> a or b }
+
+fun UByteArray.xorInto(
+    that: UByteArray,
+    destination: UByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    thatStartIndex: Int = 0,
+) = combineInto(
+    that,
+    destination,
+    destinationOffset,
+    startIndex,
+    endIndex,
+    thatStartIndex,
+) { a, b -> a xor b }
+
+infix fun UByteArray.xor(that: UByteArray) =
+    combine(that) { a, b -> a xor b }

src/commonMain/kotlin/com/infendro/bytes/ubytearray/String.kt

@@ -0,0 +1,7 @@
+package com.infendro.bytes.ubytearray
+
+fun String.encodeToUByteArray(): UByteArray =
+    encodeToByteArray().asUByteArray()
+
+fun UByteArray.decodeToString(): String =
+    asByteArray().decodeToString()

src/commonMain/kotlin/com/infendro/bytes/uint/Conversion.kt

@@ -0,0 +1,16 @@
+package com.infendro.bytes.uint
+
+import com.infendro.bytes.ByteOrder
+import com.infendro.bytes.ByteOrder.BIG_ENDIAN
+
+fun UInt.toUByteArray(order: ByteOrder = BIG_ENDIAN) =
+    UByteArray(4).also { copyInto(it, order = order) }
+
+fun UInt.toByteArray(order: ByteOrder = BIG_ENDIAN) =
+    ByteArray(4).also { copyInto(it, order = order) }
+
+fun UIntArray.toUByteArray(order: ByteOrder = BIG_ENDIAN) =
+    UByteArray(size * 4).also { copyInto(it, order = order) }
+
+fun UIntArray.toByteArray(order: ByteOrder = BIG_ENDIAN) =
+    ByteArray(size * 4).also { copyInto(it, order = order) }

src/commonMain/kotlin/com/infendro/bytes/uint/Copy.kt

@@ -0,0 +1,59 @@
+package com.infendro.bytes.uint
+
+import com.infendro.bytes.ByteOrder
+import com.infendro.bytes.ByteOrder.BIG_ENDIAN
+import com.infendro.bytes.ByteOrder.LITTLE_ENDIAN
+
+fun UInt.copyInto(
+    destination: UByteArray,
+    destinationOffset: Int = 0,
+    order: ByteOrder = BIG_ENDIAN,
+) {
+    require(destinationOffset in 0..(destination.size - 4))
+
+    when (order) {
+        BIG_ENDIAN -> {
+            destination[destinationOffset] = (this shr 24).toUByte()
+            destination[destinationOffset + 1] = (this shr 16).toUByte()
+            destination[destinationOffset + 2] = (this shr 8).toUByte()
+            destination[destinationOffset + 3] = this.toUByte()
+        }
+        LITTLE_ENDIAN -> {
+            destination[destinationOffset] = this.toUByte()
+            destination[destinationOffset + 1] = (this shr 8).toUByte()
+            destination[destinationOffset + 2] = (this shr 16).toUByte()
+            destination[destinationOffset + 3] = (this shr 24).toUByte()
+        }
+    }
+}
+
+fun UInt.copyInto(
+    destination: ByteArray,
+    destinationOffset: Int = 0,
+    order: ByteOrder = BIG_ENDIAN,
+) = copyInto(destination.asUByteArray(), destinationOffset, order)
+
+fun UIntArray.copyInto(
+    destination: UByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) {
+    val length = endIndex - startIndex
+    require(length >= 0)
+    require(startIndex in 0..(size - length))
+    require(destinationOffset in 0..(destination.size - (length * 4)))
+
+    repeat(length) { i ->
+        this[startIndex + i].copyInto(destination, destinationOffset + (i * 4), order)
+    }
+}
+
+fun UIntArray.copyInto(
+    destination: ByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) = copyInto(destination.asUByteArray(), destinationOffset, startIndex, endIndex, order)

src/commonMain/kotlin/com/infendro/bytes/ulong/Conversion.kt

@@ -0,0 +1,16 @@
+package com.infendro.bytes.ulong
+
+import com.infendro.bytes.ByteOrder
+import com.infendro.bytes.ByteOrder.BIG_ENDIAN
+
+fun ULong.toUByteArray(order: ByteOrder = BIG_ENDIAN) =
+    UByteArray(8).also { copyInto(it, order = order) }
+
+fun ULong.toByteArray(order: ByteOrder = BIG_ENDIAN) =
+    ByteArray(8).also { copyInto(it, order = order) }
+
+fun ULongArray.toUByteArray(order: ByteOrder = BIG_ENDIAN) =
+    UByteArray(size * 8).also { copyInto(it, order = order) }
+
+fun ULongArray.toByteArray(order: ByteOrder = BIG_ENDIAN) =
+    ByteArray(size * 8).also { copyInto(it, order = order) }

src/commonMain/kotlin/com/infendro/bytes/ulong/Copy.kt

@@ -0,0 +1,67 @@
+package com.infendro.bytes.ulong
+
+import com.infendro.bytes.ByteOrder
+import com.infendro.bytes.ByteOrder.BIG_ENDIAN
+import com.infendro.bytes.ByteOrder.LITTLE_ENDIAN
+
+fun ULong.copyInto(
+    destination: UByteArray,
+    destinationOffset: Int = 0,
+    order: ByteOrder = BIG_ENDIAN,
+) {
+    require(destinationOffset in 0..(destination.size - 8))
+
+    when (order) {
+        BIG_ENDIAN -> {
+            destination[destinationOffset] = (this shr 56).toUByte()
+            destination[destinationOffset + 1] = (this shr 48).toUByte()
+            destination[destinationOffset + 2] = (this shr 40).toUByte()
+            destination[destinationOffset + 3] = (this shr 32).toUByte()
+            destination[destinationOffset + 4] = (this shr 24).toUByte()
+            destination[destinationOffset + 5] = (this shr 16).toUByte()
+            destination[destinationOffset + 6] = (this shr 8).toUByte()
+            destination[destinationOffset + 7] = this.toUByte()
+        }
+        LITTLE_ENDIAN -> {
+            destination[destinationOffset] = this.toUByte()
+            destination[destinationOffset + 1] = (this shr 8).toUByte()
+            destination[destinationOffset + 2] = (this shr 16).toUByte()
+            destination[destinationOffset + 3] = (this shr 24).toUByte()
+            destination[destinationOffset + 4] = (this shr 32).toUByte()
+            destination[destinationOffset + 5] = (this shr 40).toUByte()
+            destination[destinationOffset + 6] = (this shr 48).toUByte()
+            destination[destinationOffset + 7] = (this shr 56).toUByte()
+        }
+    }
+}
+
+fun ULong.copyInto(
+    destination: ByteArray,
+    destinationOffset: Int = 0,
+    order: ByteOrder = BIG_ENDIAN,
+) = copyInto(destination.asUByteArray(), destinationOffset, order)
+
+fun ULongArray.copyInto(
+    destination: UByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) {
+    val length = endIndex - startIndex
+    require(length >= 0)
+    require(startIndex in 0..(size - length))
+    require(destinationOffset in 0..(destination.size - (length * 8)))
+
+    repeat(length) { i ->
+        this[startIndex + i].copyInto(destination, destinationOffset + (i * 8), order)
+    }
+}
+
+fun ULongArray.copyInto(
+    destination: ByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) = copyInto(destination.asUByteArray(), destinationOffset, startIndex, endIndex, order)